"I'm running the New York Marathon this year and raising funds for the J/P Haitian Relief Organization (Can you believe it?)" the actress announced. "Together, I hope we can raise at least $500,000 and make a huge impact in this magical country."

The onetime Playboy model said she is "passionate about the cause" and will keep friends and followers updated on her training and progress through social media. She also included an ode to the poverty-stricken nation.

"To spend time in Haiti is to fall in love with Haiti The magic of this country… The people… The humility… Pride Musicians, athletes and Artists It has been heartbreaking to witness the poverty among people in what should be a very rich country," she wrote on her runner's page.

She also said she'd visited the island nation shortly after the magnitude-7.0 earthquake earthquake in January 2010 and helped with local farms, food distribution in tent camps and even "brought cold beer through rubble-covered streets to volunteers."

"People do things for other people that they wouldn't ordinarily do for themselves," she told the New York Daily News. "Haiti is such a magical place. It has a real special place in my heart.... I have a lot of faith that I will be able to get through it. I'm committed. People tell me that I really don’t know what I'm getting into, but that’s kind of the story of my life. I'll just go with it."

The 26.2-mile run will take place on Nov. 3, and Anderson admitted that she's working on boosting her stamina with the elliptical and StairMaster machines, doing ab workouts at home, lifting 5-pound weights, doing Pilates and "moving my body as much as I can," Anderson told the newspaper. She added that she's also "running different distances on different surfaces."

After having two boys with ex-husband Tommy Lee, Anderson didn't believe she'd be able to shed her baby weight, but she revealed that she now weighs only 115 pounds but is in the best shape of her life.

"The weight I gained from having two kids, thinking I might have to hang onto that for the rest of my life, is gone," she said. "My legs feel strong.... I feel like a lean machine."

The animal-rights activist is also vegetarian is also watching her diet as she trains, drinking juices and smoothies and eating plenty of vegetables, brown rice and quinoa.

"My refrigerator is full of kale and greens," she said. "I can’t imagine something greasy or eating meat."

However, she did admit to cheating on her diet with cappuccinos and chocolate.

The blond bombshell has previously participated in "Dancing With the Stars" and Britain's "Dancing on Ice," and she plans to treat this marathon just like those shows: as a learning experience.

"People think I'm crazy," Anderson told the New York Daily News. "I like to do things that people think maybe I can't do, and this is definitely one of those things. You know, somehow I learned to dance, learned to skate, and all these things that people thought I couldn't do. Now, I'm running a marathon."